6p1p tube

[emosms]

Hi, anyone tried to run these over the max datasheet rating of 250v?
In my case 330/340v, push pull amp.
Not aiming for max output (I will set the max current not to exceed the max plate dissipation).
It is just the psu/transformer I have

[J M Fahey]

Try it, it should work.
Just don´t overheat them to death.

If anything, take care of screens.

Unless tests suggest otherwise, I would add, say, 1 k resistors in series with each, just to play it safe.

[emosms]

You mean 1k in series with each screen grid?

Haven't started on the output stage design yet, but if I aim for 15/16 ohm speaker, the OT primary impedance would be higher, so the higher power supply won't be a problem?

[Chuck H]

If you use cathode bias you'll trim the actual "working voltage" of the tubes by the amount standing on the cathode. Working voltage would be the effective plate voltage. If you want fixed bias you can use a zener across the cathode resistor with a ZV close to the measured cathode voltage.

[J M Fahey]

You mean 1k in series with each screen grid?

Haven't started on the output stage design yet, but if I aim for 15/16 ohm speaker, the OT primary impedance would be higher, so the higher power supply won't be a problem?

Plates are large pieces of sheet metal, dark matte surface (higher IR emission), have high-ish thermal mass, can stand red plating for a long time, abusing them is not that bad

Can stand higher voltage unless you get crazy and approach arcing voltages.

While screens are made out of *thin* wire, zero thermal mass, easy to destroy.

That´s why current limiting resistors are often a good idea and it is better NOT to overvolt them.